When a detector of a photon counting type (hereinafter, “photon counting detector”) is structured as an area detector, Application Specific Integrated Circuits (ASICs) are arranged in a highly concentrated manner to be positioned very close to the photon counting detector, to measure small output electric currents from the photon counting detector. While acquiring count results, the ASICs generate heat in accordance with count rates thereof. Because the ASICs are arranged in the vicinity of the photon counting detector, the heat generated by the ASICs is easily transferred to the detector.
To cope with this situation, a method has been proposed by which a heater is provided in the vicinity of a photon counting detector so as to exercise control to keep the photon counting detector at a constant temperature by using an output from a temperature sensor as a control signal. Further, another method has also been proposed by which, without using a temperature sensor, the temperature of a photon counting detector is controlled by conjecturing the temperature on the basis of a dark current value obtained from the photon counting detector prior to a scan.